Protected metal article



Aug 2, 1955 A. w. coFFMAN ETAL 2,714,246

PROTECTEDl METAL ARTICLE Filed Sept. 9, 1950 ATTORNEY United States Patent O PROTECTED METAL ARTICLE Application September 9, 1950, Serial No. 184,090

7 Claims. (Cl. 29-195) This invention relates to a protected metal article.

The object of the invention is to produce a novel and superior protected metal article of the general type disclosed in the United States patents to Coffman, Nos. 1,862,332 and 2,073,334, and wherein the fibrous sheet is secured in a novel and superior manner to the metal core sheet.

With this general object in view and such others as may hereinafter appear, the invention consists in the protected metal article, hereinafter described and particularly defined in the claims at the end of this specification.

ln the drawings illustrating the preferred embodiment of the present invention, Fig. l is a cross-sectional view of a protected metal article embodying the present invention; Fig. 2 is a side elevation of apparatus which may be employed in practicing the preferred method of producing the present article; Fig. 3 is a cross-sectional view of the article in the process of being produced, the section being taken on the line 3-3 of Fig. 2; and Fig. 4 is a crossscctional view of a modified form of apparatus including an additional step which may be employed in practicing the present method.

Prior to the present invention, the protected metal building sheets disclosed in the Coffman Patents 1,862,332 and 2,073,334 have been produced commercially in large quantities. During the development of the commercial process it has been found that the process disclosed in the second Coffman Patent 2,073,334 has been the more practical process for the reason that in the process disclosed in the Coffman Patent 2,073,334 the fibrous sheets were pressed into the galvanizing coating upon the steel sheet before the galvanizing coating had an opportunity to solidify, and as a result the tendency of the zinc coating to oxidize was avoided. When the process of the first Coffman Patent 1,862,332 was followed some difliculty was experienced in producing most efficient adhesion because of the fact that any substantial amount of oxidzation of the zinc coating when the galvanized sheets were reheated seriously interfered with the most successful bonding of the fibrous sheets to the steel coatin 8The present invention represents an improvement upon the process disclosed in the aforementioned Coffman patents and contemplates the sprinkling or distribution of additional metal adhesive in a solidified finely divided form on to the metal sheet which has been previously coated with the metal adhesive. When zine is used as the metal adhesive additional powdered zinc is sprinkled or distributed on to the previously galvanized metal sheet. The sheet in this condition is then heated to a point above the softening point of the zinc or other metal adhesive, and then the fibrous sheet or sheets are pressed into the surface or surfaces, preferably by passing the assembly between combining rolls. lf preferred, the galvanized sheet immediately after it leaves the galvanizing bath may have the powdered zine applied to the molten galvanizing coating before the latter has solidified and then passed rapidly through combining rolls between enveloping 2,714,246 Patented Aug. 2, 1955 sheets of fibrous material before substantial cooling of the zinc-coated sheet has occurred. The relatively large heat capacity of the hot zinc-coated steel sheet as compared with that of the small particles of zinc is such that the latter are heated adequately without cooling the former below the point when successful bonding to the fibrous material is accomplished. As an alternativey pro` cedure, the metal powder may be sprinkled upon the surface of the fibrous material on the side of the sheet which will contact the coated metal core sheet. After the assembly has been passed through the combining rolls it is cooled, producing a laminated product wherein the additional particles of zinc are bonded to the metal galvanizing coating and extend up into the body of the fibrous sheet, penetrating several layers of the fibers. These individual particles of powdered zinc serve more or less as rivets by reason of the fact that during the combining of the felt with the sheet as the assembly is passed between the combining rolls, the individual particles are upset and clinched over the fibers through which they penetrate. ln addition to the superior bonding effect the present protected metal article is provided with an additional amount of zinc as compared with previous comparable products produced in accordance with the disclosures of the two Coffman patents above referred to, and this additional supply of zinc furnishes additional cathodic protection during weather exposure of the sheets in their use as roofing and siding sheets.

Referring to the drawing which illustrates the preferred method of producing a protected metal sheet suitable for use as a roofing or siding sheet, 10 represents a metal sheet, and preferably a steel sheet, having secured to the opposite surfaces thereof layers 12, 14 of fibrous materials, such as asbestos paper or felt, by an interposed layer of metal adhesive 16, such as zinc. The zinc layers 16 are bonded to the metal core sheet 10 and are keyed to the fibrous layers. The layers of metal adhesive 16 are also provided with a large number of small particles 18. also of metal adhesive, and which may be initially applied to a previously coated metal sheet, such as previously galvanized metal sheet, or they may be applied on the surface of the galvanized or other coating immediately after the galvanizing operation and before the galvanizing coating has solidified. As shown in Fig. l, these small particles or protuberances of metal adhesive are in the protected metal article, bonded to the metal adhesive layer and are themselves keyed and clinched to the fibrous layers as more or less diagrammatically illustrated in Fig. 1.

In Fig. 2, we have illustrated the preferred apparatus for practicing the present method of producing the improved protected metal sheet, and as therein shown, a previously galvanized steel sheet indicated at 20 is conveyed horizontally under a sifting hopper 22 containing a supply of the finely divided metal adhesive, which is to be applied to the metal sheet to form the protuberances 18, above referred to. Preferably, the finely divided metal adhesive comprises zinc powder or zine dust, and as the metal sheet is passed under the sprinkling hopper a light sprinkle of the zinc dust 24 is applied to the upper surface of the sheet. The sheet thus prepared is then conveyed by an endless conveyor 26 through a heating furnace, preferably an electric heating furnace, indicated more or less diagrammatically at 28, where the sheet is heated to a temperature above the softening point of the metal adhesive to thereby fuse the individual particles of' zinc 18 to the surface of the metal adhesive layer 16, which in the present instance comprises the previously applied zinc coating resulting from the previous galvanizlng operation. Immediately after the metal sheet 20 emerges from the heating furnace 28, and before both the metal adhesive layer 16 and the protuberances 18 have adhesive of both the original or primary adhesive layer 16 and the protuberances 18 with thetresult that after the sheet has passed between the combining rolls 30', 32

the fibrous layer 12 has been firmly keyed to the metal adhesive layer 16 and to the protuberances 18, the latter penetrating through a substantial portion of the fibrous web 12 with the result that superior bonding results. In addition, the protuberances 18 are clinched' over and around the adiacent fibers of the web 12 so that the fibrous layer 12 is firmly and mechanically anchored to the metal adhesive layer, and consequentlyto the core sheet 10.

The process thus far described may be followed in applying the powdered zinc to one surface of the sheet, and in those instances where it is desired to apply the same to both sides of the galvanized sheet, the sheet may be turned over and the operations repeated.

In many instances, in practice, it is preferred to provide fibrous layers upon both sides of the metal core sheet, and conveniently this may be accomplished by the application of the finely divided metal adhesive particles 24 to the upper surface of a second web of fibrous material 14 as the latter is drawn from a supply, roll 36 and fed beneath a second sprinkling hopper 38, as indicated in Fig. 2. The metal particles 18 are pressed into the surface of the web sufficiently to enable the metal particles to adhere thereto until the sheet is conducted between the combining rolls 30, 32 during the passage of the sheet around an idler roll 33. During the passage of the web 14 with the protuberances 18 thereon between the combining rolls 30, 32 an action takes place similar to that previously described so that the lower web 14 is keyed to the metal adhesive 16 and also mechanically clinched by the protuberances 18 as indicated in Fig. l.

From the description thus far it will be apparent that in the apparatus illustrated in Fig. 2, the method above described for producing the metal adhesive 16 on the steel or other metal core sheet, and the operation of combining the metal sheet and fibrous layers,V comprise separate operations, thus enabling each operation to be controlled independently of the other. In other words, in practlce, previously galvanized steel sheets will be fed into one end of the apparatus shown in Fig. 2, and the rate of feed and the rate at which the zinc powder is applied together with the speed of operation of the combining rolls 30, 32 may be accurately controlled independently of one another in order to secure the most advantageous combining operation.

For some purposes, however, it may be desirable to apply the zinc or other metal adhesive powder to the surface of the galvanized sheet as the latter emerges from the galvanizing bath 40, as shown in Fig. 4. In such instances the sprinkling hopper 46 will be located adjacent the galvanizing bath 40 so that the galvanized sheet may be passed thereunder to be supplied with the stream of zine dust or zine powder 48 prior to the cooling of the zinc coating on the galvanizing sheet. Thereafter the remainder of the voperation may and preferably will be carried on as indicated in the apparatus shown in Fig. 2, and as above described. The galvanizing bath 40 may and preferably will be heated in the usual manner and be provided with the usual fiux box 42 and exit rolls 44.

In practicing the present invention we have obtained satisfactory results utilizing the apparatus shown in Fig. 2 wherein previously galvanized steel sheets are fed into the apparatus and wherein the temperature of the heating oven 28 is maintained between 450 to 550 degree centigrade. We have also observed that some overheating does not detract appreciably from the resulting adhesion obtained. The zinc powder may be of varying degrees of flneness,

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and wc have experienced satisfactory results utilizing a pamt grade zinc dust as well as a relatively coarser powder. The paint grade of zinc dustis of a degree of fineness approximately 90% finer than 325 mesh. An amount of such powder was sprinkled on to the sheets at a rate `of approximately 2.4 grams per square foot, or 0.53 lb. per hundred square feet. When relatively coarser zinc powder was utilized most of the particles were between 35 and 200 mesh, and these were sprinkled upon sheets at the rate of 1.38 grams per square foot, or approximately 0.31 lb. perV hundred square feet. While the foregoing figures indicate the type of zinc powders and the amounts thereof which we have found to produce satisfactory results, nevertheless, it is not desired to limit the invention in this respect.

For the production of building sheets for roofing and siding purposes where the sheets are'to be corrugated, a practical limit exists as to the thickness of the ordinary galvanizing coating which may be applied to the Ysteel Beyond this thickness the galvanizing coating cracks, breaks loose from the steel and tends to scale off. In practicing the present process, however, it has been found that the additional zinc supplied in the form of a sprinkled powder entirely overcomes this prior disadvantage and enables far more zinc to be applied to the sheets while still maintaining their ability to be corrugated without cracking, than was the ease with the ordinary galvanized sheet.

From the above description it will be observed that asbestos felt may be successfully combined with a previously coated and reheated steel sheet irrespective of any oxide formation during the reheating. The additional zinc initially applied in the form of zinc powder or dust is fused with the galvanized coating of the reheated sheet and forms a plurality of spaced protuberances which penetrate several layers of fibers when the felt is pressed into the metal adhesive and the ends of the protuberances provide additional grip as the protuberances are upset under the pressure of the combining rolls to clinch over the fibers through which they have penetrated, as indicated at 50 in Fig. l, thus forming a firm and secure bond. A steel sheet thus protected in accordance with the present invention is extremely durable and may be formed into various shapes with minimum liability of damage to the protective coating thereof.

While it is preferred to utilize a galvanized steel sheet and powdered zinc in the production of the present protected metal sheet, it will be understood that other fusible metals and alloys may be used instead of the galvanizing and powdered zinc, such for example as tin, lead, cadmium, and the like.

While the preferred embodiment of the invention has been herein illustrated and described, it will be understood that the invention may be embodied in other forms within the scope of the following claims.

. Having thus described the invention, what is claimed is' having both surfaces thereof coated with a continuous layer of metal adhesive alloyed to the metal sheet, and a layer of fibrous material covering each surface of the thus coated metal sheet, a series of small individual solid particles of the metal adhesive spaced from adjacent partiicles and alloyed with the continuous coating of metal adhesive on each surface of the metal core sheet and upstanding a. substantial distance therefrom and projecting into and mechanically keyed to the body of each fibrous layer, said fibrous layers being bonded to the continuous coatings between said small individual solid particles of metal adhesive.

2. As a new article of manufacture, a metal sheet having one surface thereof coated with a continuous layer of metal adhesive alloyed to the metal sheet and having a layer of fibrous material covering said coated surface a series of small individual solid particles of the metal l. As a new article of manufacture, a metal core sheet 5 adhesive spaced from adjacent particles and alloycd with the continuous coating of metal adhesive and upstanding therefrom and projecting into and mechanically keyed to the body of said fibrous layer, said fibrous layer being bonded to the continuous coating between said small individual solid particles of metal adhesive.

3. As a new article of manufacture, a galvanized steel sheet having the opposite surfaces thereof each provided with a fibrous sheet covering the same, a series of small individual zinc particles fused to the galvanizing coating on each surface of the metal sheet and upstanding therefrom and spaced from adjacent particles, said particles projecting into and being mechanically keyed into each fibrous sheet, and said fibrous sheets being bonded to the galvanizing coatings between said small individual solid particles. Y

4. As a new article of manufacture, a galvanized steel sheet provided upon one surface thereof with a brous sheet covering the same, a series of small individual solid particles of zinc fused to the galvanizing coating and projecting into and mechanically keyed into the body of the fibrous sheet and spaced from adjacent particles, said fibrous sheet being bonded to the galvanizing coating between said small individual solid particles of zinc.

5. A protected metal article comprising a metal article having a surface thereof coated with a continuous layer of metal adhesive alloyed to the metal article and having a layer of fibrous material covering said surface, i

a series of small individual solid particles of the metal adhesive between said brous layer and said metal article and alloyed with said continuous coating of metal adhesive, said small individual and spaced particles projecting a substantial distance into and being mechanically 6 keyed to the body ofthe fibrous layer, and the fibrous layer being bonded to the continuous coating between said small individual and spaced particles.

6. As a new article of manufacture, a protected metal sheet as defined in claim 1 wherein the free ends of the discrete metal particles are clinched over bers of the brous material adjacentthereto.

7. As a new article of manufacture, a protected metal article as defined in claim 5 wherein the free ends of the discrete metal particles are clinched over fibers of the fibrous layer adjacent thereto.

References Cited in the le of this patent UNITED STATES PATENTS 1,412,326 Williams Apr. 11, 1922 1,720,708 Young July 16, 1929 1,767,421 Wirth June 24, 1930 1,807,875 Robinson June 2, 1931 1,844,512 Mains Feb. 9, 1932 1,862,332 Coffman June 7, 1932 2,052,585 Tannewitz Sept. 1, 1936 2,068,533 Coffman 2--.. 1an. 19, 1937 2,073,334 Coffman Mar. 9, 1937 2,157,456 Koyemann May 9, 1939 2,188,434 Grinter Jan. 30,v 1940 2,284,254 Batcheller VMay 26. 1942 2,340,227 Russell Jan. 25, 1944 2,355,949 Boutwell Aug. 15, 1944 2,600,220 Doelker June 10, 1952 FOREIGN PATENTS 227,383 Great Britain Ian. 15, 1925 

1. AS A NEW ARTICLE OF MANUFACTURE A METAL CORE SHEET HAVING BOTH SURFACES THEREOF COATED WITH A CONTINUOUS LAYER OF METAL ADHESIVE ALLOYED TO THE METAL SHEET, AND A LAYER OF FIBROUS MATERIAL COVERING EACH SURFACE OF THE THUS COATED METAL SHEET, A SERIES OF SMALL INDIVIDUAL SOLID PARTICLES OF THE METAL ADHESIVE SPACED FROM ADJACENT PARTIICLES AND ALLOYED WITH THE CONTINUOUS COATING OF METAL ADHESIVE ON EACH SURFACE OF THE METAL CORE SHEET AND UPSTANDING A SUBSTANTIAL DISTANCE THEREFROM AND PROJECTING INTO AND MECHANICALLY KEYED TO THE BODY OF EACH FIBROUS LAYER, SAID FIBROUS LAYERS BEING BONDED TO THE CONTINUOUS COATINGS BETWEEN SAID SMALL INDIVIDUAL SOLID PARTICLES OF METAL ADHESIVE. 